Tag: Voyager Program

The NASA probe was launched in 1977 and has now joined its twin, Voyager 1, to begin a new chapter of interstellar discovery

Both Voyager 1 and 2 are sampling particles from the interstellar medium, becoming humanity’s furthest-flung missions into deep space [NASA/JPL-Caltech]

Carolyn Porco, planetary scientist and lead of the NASA Cassini mission imaging team, probably said it best:

Voyager 1 made us an interstellar species; 6 yrs later, Voyager 2 makes it look easy. While these are historic, soul-stirring achievements, I am most happy right now that Ed Stone, the best Project Scientist who ever lived, lived to see this moment.

It can be easy to lump today’s announcement about Voyager 2 entering interstellar space as “simply” another magnificent science achievement for NASA — but that would be too narrow; the Voyager spacecraft have become so much more. They represent humanity at our best; our will to explore, our need to push boundaries, our excitement for expanding the human experience far beyond terrestrial shores. They also act as a means to understand the sheer scale of our solar system. And what better way to measure that scale than with a human life.

Ed Stone started working on the Voyager Program in 1972 as a project scientist. Now, at 82 years old, he’s still working on the Voyagers nearly half a century later as they continue to send back data from the frontier beyond our solar system. When we start measuring space missions in half-centuries, or missions that have lasted entire careers, it becomes clear how far we’ve come. Not only does NASA build really tough space robots that surpass expectations routinely, returning new discoveries and revelations about the universe that surrounds us, the Voyagers have become a monument to the essence of being human, something with which Stone would probably agree.

Although most of the instruments aboard the Voyagers are no longer functional, both missions are still returning data from the shores of the interstellar ocean and, on Nov. 5, mission controllers noticed that one of Voyager 2’s instruments, the Plasma Science Experiment (PSE), had detected a rapid change in its surrounding environment. Used to being immersed the comparatively warm and tenuous solar wind flowing past it, its plasma measurements detected a change. The spacecraft had passed into a region of space where the plasma was now denser and cooler. Three other particle experiments also detected a dramatic change; solar wind particle counts were down, but cosmic ray counts precipitously increased. Voyager 1’s PSE failed in 1980, so couldn’t measure this boundary when it entered interstellar space in 2012, so Voyager 2 is adding more detail about what we can expect happens when a spacecraft travels from the heliosphere, through the heliopause and into interstellar space.

[NASA/JPL-Caltech]

“There is still a lot to learn about the region of interstellar space immediately beyond the heliopause,” said Stone in a NASA statement.

The heliosphere can be imagined as a vast magnetized bubble that is generated by the Sun. This bubble is inflated by the solar wind, a persistent stream of solar particles that ebb and flow with the Sun’s 11-year cycle. When the Sun is at its most active, the bubble expands; at its least active, it contracts. This dynamic solar sphere of influence affects the flux of high-energy cosmic rays entering the inner solar system, but the physics at this enigmatic boundary is poorly understood. With the help of the Voyagers, however, we’re getting an in-situ feel for the plasma environment at the boundary of where the Sun’s magnetism hits the interstellar medium.

To achieve this, however, we had to rely on two spacecraft that were launched before I was born, in 1977. Voyager 2 is now 11 billion miles away (Voyager 1 is further away, at nearly 14 billion miles) and it took the probe 41 years just to reach our interstellar doorstep. Neither Voyagers have “left” the solar system, not by a long shot. The gravitational boundary of the solar system is thought to lie some 100,000 AU (astronomical units, where one AU is the average distance from the Earth to the Sun), the outermost limit to the Oort Cloud — a region surrounding the solar system that contains countless billions of icy objects, some of which become the long-period comets that intermittently careen through the inner solar system. Voyager 2 is barely 120 AU from Earth, so as you can see, it has a long way to go (probably another 30,000 years) before it really leaves the solar system — despite what the BBC tells us.

So, tonight, as we ponder our existence on this tiny pale blue dot, look up and think of the two space robot pioneers that are still returning valuable data despite being in deep space for over four decades. I hope their legacy lives on well beyond the life of their radioactive generators, and that the next interstellar spacecraft (no pressure, New Horizons) lives as long, if not longer, than the Voyagers.

UPDATE 1:That whole thing I said in my Al Jazeera English op-ed about being blinkered on the organics explanation for the “big” news on Monday? Well, case in point, as tweeted by @MarsToday on Sunday night, perhaps Curiosity has discovered further evidence for perchlorates on Mars. I have no clue where this information is sourced, and I’m not going to speculate any more, but if perchlorates have been discovered in Gale Crater, it would support the findings of NASA’s 2008 Mars Phoenix lander findings of perchlorate and possible liquid water brine in the arctic regions of the Red Planet. Place your bets…

Over the last bizarre few days, a key NASA scientist (almost) spilled the beans on a “historic” discovery by the Mars Science Laboratory (MSL) rover Curiosity. Then, speculation ran wild. Had NASA’s newest Mars surface mission discovered organics? Feeling the need to stamp out the glowing embers of organic excitement ahead of the Dec. 3 AGU press conference, NASA said that there would be no big announcement on Monday. But then the agency went even further, issuing a terse statement to point out that the speculation is wrong. “At this point in the mission, the instruments on the rover have not detected any definitive evidence of Martian organics,” said NASA.

So now we’re left, understandably, wondering what lead MSL scientist John Grotzinger was referring to. I think it’s safe to assume that he wasn’t misquoted by the NPR journalist who happened to be sitting in his office when the MSL team was receiving data from the mission’s Sample Analysis at Mars (SAM) instrument. And if we take NASA’s damage-controlling statements at face value, Grotzinger was just getting excited for all the data being received from the rover — after all, the entire mission is historic.

As a science media guy with a background in science, I totally ‘get’ what the MSL team are going through. Scientists are only human and whether or not Grotzinger was getting excited for a specific “historic” find or just getting generally excited for all the “historic” data streaming from the rover, is irrelevant. Perhaps he should have been more careful as to the language he used when having an NPR reporter sitting in the same room as him, but that’s academic, I’m pretty sure that if I was leading the most awesome Mars mission in the history of Mars missions I’d be brimming over with excitement too. The scientific process is long and can often seem labored and secretive to the media and public — rumors or a few slipped words from scientists is often all that’s needed to spawn the hype. But for the scientific process to see its course, data needs to be analyzed, re-analyzed and theories need to be formulated. In an announcement as important as “organics on Mars,” the science needs to be watertight.

However, I can’t help but feel that, in NASA’s enthusiasm to “keep the lid” on speculation, that they are setting themselves up for a backlash on Monday.

If the AGU press conference is just “an update about first use of the rover’s full array of analytical instruments to investigate a drift of sandy soil,” as the NASA statement says, won’t there be any mention of organics? Will this be a similar announcement to the sampling of Mars air in the search for methane? The upshot of that Nov. 2 press conference was that the Mars air had been tested by SAM and no methane (within experimental limits) had been discovered… yet. But this was a sideline to the announcement of some incredible science as to the evolution of the Martian atmosphere.

This time, although there may not be “definitive,” absolute, watertight proof of organics, might mission scientists announce the detection of something that appears to be organics… “but more work is needed”? It’s a Catch 22: It’s not the “historic” news as the experiment is ongoing pending a rock-solid conclusion; yet it IS “historic” as the mere hint of a detection would bolster the organics experiments of the Viking landers in the 1970s and could hint at the discovery of another piece of the “Mars life puzzle.” And besides, everything Curiosity does is “historic.”

In NASA’s haste to damper speculation, have they cornered themselves into not making any big announcements on Monday? Or have they only added to the speculation, bolstering the media’s attention? Besides, I get the feeling that the media will see any announcement as a “big” announcement regardless of NASA scientists’ intent. Either way, it’s a shame that the hype may distract from the incredible science the MSL team are carrying out every single day.

Meanwhile, in deep space, a little probe launched 35 years ago is edging into the interstellar medium and NASA’s Voyager Program team are also holding an AGU press conference on Monday. Although there have been no NPR journalists getting the scoop from mission scientists, it’s worth keeping in mind that Voyager 1 really is about to make history. In October, I reported that the particle detectors aboard the aging spacecraft detected something weird in the outermost reaches of the Solar System. As Voyager 1 ventures deep into the heliosheith — the outermost component of the heliosphere (the Sun’s sphere of influence) — it detected inexplicable high-energy particles. The theory is that these particles are being accelerated by the magnetic mess that is the outermost reaches of the Solar System. But there is growing evidence in particle detections and magnetometer readings that the probe may have just left the Solar System, completely escaping the heliosphere.

A big hint is in the following graphs of data streaming from Voyager 1. The first plot shows the increase in high-energy cosmic ray particle counts. These high-energy particles typically originate from beyond the heliosphere. The bottom plot shows lower-energy particles that originate from the solar wind. Note how the lower-energy particle counts fell off a cliff this summer, and how the high-energy particles have seen a marked increase at around the same period:

High-energy cosmic ray count as detected by Voyager 1. Credit: NASA

Low-energy cosmic ray count as detected by Voyager 1. Credit: NASA

So, in light of the media-centric Curiosity debate over what is “historic” and what’s not “historic” enough to be announced at conferences, I’m getting increasingly excited for what the Voyager team have got to say tomorrow. It’s inevitable that Voyager 1 will leave the Solar System, but will NASA call it at the AGU? Who knows, but that would be historic, just without the hype.